Hydraulically operated gas compressor



Oct. 20,1959 A. c. sAMPll-:TRO

HYDRAULICALLY opgmm GAS couPREssoR Filed oct. 1o. 195e HYDRAULICALLY OPERATED GAS COMPRESSOR Achilles C. Sampetro, Detroit, Mich., assignor to Thompson Ramo Wooldridge Inc., a corporation of Ohio Application October 10, v1956, Serial No. 615,066 l11 claims. (ci. 23o- 52) The present invention relates to improvents in reciproeating gas compressors operated by pressurized fluid and to the combined controls for the compressor.

The present invention contemplates the provision of a gas compressor employing a cylindrically shaped closed compression chamber with a reciprocating compression piston slidably mounted therein and operable in a compression and intake stroke to force compressed gas or the like out through a compressor delivery conduit, and to take in gas through a gas intake conduit, which is also connected to the back side of the piston, with the ow through the conduits being controlled by non-return check valves. Reciprocation of the piston is obtained through a smaller diameter piston extension slidably housed in a cylindrically hollow compressed iluid chamber within the main chamber to which compressed fluid is supplied by a control valve. Fluid leaksV from the fluid chamber during the compression stroke of the piston through lateral openings to a chamber formed by a' bellows attached to the fluid side of the piston and tothe end of the chamber. The control valve alternately vents and admits pressurized fluid to the fluid chamber and is electrically operated by apressure responsive switch which includes delay elements to insure that the piston will complete its compression and intake strokes before the control valve changes position.

An object of the invention is to provide a compressor in accordance 'with the above vcontemplated structure and operation wherein the flow of pressurized working fluid is regulated by an electrically operated control valve.

Another object of the invention is to provide an improved gas compressor wherein the working fluid is at a higher pressure than the compressed gas.

Another object of the invention is to provide an irnproved gas compressor wherein aV compressing piston movable in a compression cylinder is employed and the operating force is increased for the latter portion of the stroke as the resistance of the compressed gases also increases.

A still further object of the invention is to provide an improved electrical control valve for the Working fluid provided with time delay devices which permit the piston adequate time to move in its full compression and intake stroke.

Other objects and advantages will become more apparent with the teaching of the invention in the disclosure of the preferred embodiment in the specification, claims and drawing, in which:

The figure of the drawing illustrates the compressor and electrically operated control valve in vertical sectional view which is drawn partially in schematic form 2,909,315 Patented-Oct. 20, 1959 lce to` illustrate the. structure and operation of the mechamsm.

Y Although the invention is illustrated in its preferred form by certain structural features shown employed .in a combination wherein particular advantages are enjoyed, itrwill be understood that'the inventivefeatures may be utilized in other surroundings and other embodiments utilizing the advantages of the features of thev invention may be employed. l

As shown in Ithe drawing, the compressor includes a compression chamber 2, which is preferably cylindrical in shapeand includes a cylindrical outer wall 4 with end walls 6 and 8 forming the gas and. the working fluid ends of the compressor respectively. 'It will be understood that although the mediums referred to ywill be gas and iluid, that the compressor may be adapted to compressing other materials and mediums and thecompressor may be operated by various types of compressed fluids. In the preferred form, as shown, the compressor may be used for air or for material such as refrigeration fluid and the Working fluid employed may be oil. In the form shown, by Way of example the compressor is particularly well vadapted to use as a refrigeration compressor for an air conditioning unit in an automobile. In this utilization the unit maybe mounted on the front of the vehicle where it can work in comparatively cool air. In this'arrangement the Working uid is supplied by a pump operated by the automobile engine and the pressurized uid can. be .piped to various locations in the vehicle to operate other iluid motors as well as the present compressor.

`Compression is. accomplished by a piston 10 slidably mounted within the compression chamber 2. .The end 12 of theV compression chamber 2 is on the gas side of the piston 10 and' receives gasto be compressed through an intakeconduit 14 and discharges the compressed gas out through delivery conduit 16. The delivery conduit leads to an accumulator or an expansion nozzle such as commonly used in a refrigeration compressor and return of the compressed gas between each compression stroke isrprevented by a non-return valve 18, shown in the form`of a spring loaded ball check valve. The ball will unseat with each compression stroke of the piston to permit the passage of compressed gas and will return to prevent the backilow of gas when the piston moves in the intake stroke.

Similarly, the intake conduit 14 employs a non-return valve 20 which is also shown in the form of a spring loaded ball check valve. This valve opens to permit the intake of gas when the piston 10 moves in its intake stroke and closes when the piston moves in the compression stroke. The intake conduit 14 has a branch 22 which communicates with the compression chamber 4 in the zone 24, which is on the working fluid side of the piston 10. This permits the zone or chamber 24 to remain at the pressure of the intake iluid when the piston moves back and forth, and this chamber is isolated by the bellows 26, which will be described in detail later. Both conduits 14 vand 22 connect to a common conduit 28 leading to a gass supply source which may be the low pressure side of a refrigeration expansion chamber.

The piston 10 is movedV in its compression stroke by pressurized working fluid and is returned in the intake stroke by a coil helically shaped compression spring 30. This spring is located in the compression end 12 of the 3 compression chamber and will compress to a substantially Hat form when the piston is at the full end of its compression stroke. The spring has sucient strength to return the piston and force the working Huid out of the fluid chamber 32 in the intake stroke of the piston 10.

The working uid chamber 32 is dened by a cylindrically shaped wall 34 projecting into the compression chamber 2 from the wall 8 of the chamber. The hollow cyindrical wall denes the cylindrically shaped iluid chamber 32 which slidingly receives the piston extension 36, which is smaller in diameter than the main piston and which forces the piston in its compression stroke. The compression is designed to be operated by a working fluid at a higher pressure than the compression pressure. Thus the cross sectional areaof this piston extension 36 is less than the piston 10.

Working uid is forced into the uid chamber 32 through a conduit 38 leading from the control valve 40. This conduit also permits the escape of venting of the working ud when the piston extension 36 moves in the intake stroke and the pressurized fluid reaches the control valve 40 through a pressure line 42 and is vented through a return line 44, which leads back to a reservoir. The pressurized working uid may be provided from a pressure pump of any type well known to the art.

When pressurized working fluid enters the working fluid chamber 32 first to begin moving the piston extension 36 to the left as shown in the drawing, to move the piston 10 in its compression stroke, the piston extension l36 will move past the bleeder ports 46 which lead through the wall 34 of the working uid chamber 32. This permits the llow of working uid into the assist chamber 48. In the first portion of the compression stroke of the piston 10, the gas is under low pressure and the piston is thus easily moved by the pressure of the working uid against the small cross-sectional area of the end 50 of the piston extension. When the gas reaches a higher pressure, the movement of the piston 10 is assisted by the pressure of the working uid on the surface 52 which is within the bellows enclosed assist chamber 48. Thus the bleeder ports 48 will make available additional working area for the working lluid and will regulate the speed of travel of the compression piston. As the gas pressure increases the speed of travel of the piston would normally be slowed. The assist area 50 increases the force on the piston and makes its speed of travel more uniform over the full length of the compression stroke. The assist chamber is enclosed in the expansible bellows 26, which coaxially surrounds the working fluid chamber 32 and which is attached at its ends to the piston 10 and the wall 8 of the compression chamber 2. On the return or intake stroke of the piston 10 the uid is forced out of the assist chamber 48 through the same bleeder openings 46.

The control valve 40 is provided with a cylindrical valve chamber 54 having an annular pressure lluid groove 56 communicating with the pressure line. The cylindrical valve chamber also has an annular groove 58 communicating with the return line 44. Within the chamber is slidably positioned a reciprocating valve spool A60, which has a reduced center portion providing a passageway 62 which will permit communication between either the pressure groove 56 or the return groove 58, and the delivery groove 64, which communicates with the working fluid conduit 38. When the valve spool 60 is in the position shown, the pressure line 42 is in communication with the working uid conduit 38 to direct working uid to the uid chamber 32. When the spool is moved to the left, as shown in the drawing, the passageway 62 permits communication between the working uid conduit 38 and the return line 44 to permit the working fluid to leak out of the uid chamber 32, therebyy allowing piston 1t) tomove to the right'in its intake stroke.

The spool 60 of the control valve 40 is electrically Controlled and is connected to the core 66 of a solenoid 68. The solenoid coil 70 connects to a circuit having leads 72 and 74, which is controlled by pressure operated switch 76. When the solenoid coil 70 is energized, the valve is moved to the position shown in the drawing wherein the pressure line 42 is in communication with the pressure chamber 32; and when the coil is deenergized, the coil compression spring 78 pushes the valve spool to the left to cause the liuid conduit 38 to communicate with the return line 44 for the delay of pressure within the working fluid chamber 32.

The pressure switch 76 for energizing the solenoid 68 has a xed contact 80, and a movable contact 82, which is mounted on a movable diaphragm 84 within the housing of the pressure switch. The diaphragm is exposed to the pressure in the working fluid chamber 32 and for this purpose a conduit 86 is provided. In the conduit 86 is a rapid flow, slow return apparatus 88. This apparatus causes the pressure responsive switch to respond immediately to an increase in pressure in the working iluid chamber 32 and to return slowlyy with a decrease in pressure. This causes a rapid opening of the contacts 80, 82 with admission of working fluid to, the chamber 32 and a slow closing of the contacts when the Working uid pressure is permitted to decay from the chamber 32. The rapid ilow, slow return apparatus 88 is illustrated as comprising a Y-branch in the conduit 86 fwith a first small passageway 90 and a second larger passageway 92 having a ball check valve 94 therein. The ball check valve 94 opens when'the fluid pressure flows from the chamber 32 to the pressure responsive switch and closes when the uid ows in the opposite direction. Thus, when the pressure increases in the working uid chamber 32, the diaphragm 84 immediately moves to open the contacts and 82, and when the pressure drops and the iluid drains from the chamber 32, the ball check valve 94 will close making only the small passageway available for the'return of uid and there will be a substantial delay in the return of the diaphragm 48 to its normal position before the contacts 80 and 82 close. The eiect of this operation is to give the piston 10 time to return when the control valve 40 Vents the fluid to the return line 44.

The apparatus 88 provides a time delay for the piston 10 to return in its intake stroke, and the electrical storage means 94 avails a time delay for the piston to move in its compression stroke.

The electrical storage means 94 is shown in the form of a condenser connected across the leads 72 and 74 to the solenoid 70. When the switch contacts 80 and 82 open to interrupt the ow of current from a battery 96 or the like to the solenoid, the charge on the condenser 94 will maintain the solenoid energized for a short period of time to hold the control valve spool 60 in its position. When the condenser has become discharged the solenoid plunger 66 is released and the valve spool 60 moves to the ,vent position.

To explain the operation of the time delay devices 88 and 94, assume that the piston 10 is in its right hand position with the piston extension 36 fully extended into the working fluid chamber 32. At this point the switch contacts 80 and 82 are closed to energize the solenoid 68 and move the valve spool 60 to the right admitting pressurized working lluid to the chamber 32. This irnmediatcly pressurizes the chamber 32 moving the piston 10 to the left and also immediately pressurizes the prcssure switch 76 opening the contacts 80 and 82. Breaking 'the circuit through the contacts y80 and 82 will not immediately de-energize the solenoid and it will remain energized until the condenser 94 discharges. This maintains the valve spool in the pressurized position -until the piston 10 moves to the end of its compression stroke. By' this time the solenoid'will have become de-energizetl and the spring 78 will move the valve spool to the left venting the working fluid pressure chamber 32. This immediately drops the pressure in the chamber 32 and drops the pressure in the conduit 86 leading to the pressure switcli'.A The `check valve `9l4`will close, however, andthe slow, bleed of uid within the pressure switch through the passageway 90'will permit a time delaybefore the contacts 80 and 82 will close. This-will give the spring Y30 time to push the piston .10 back to the end of its intake stroke. At that time the contacts will close and the valve spool 60 will again move to its pressurized position for the beginning of a renewed cycle'of operation. Y g p Although'the overall operation of the device willl be clear from the foregoing description of the elements and the detailed discussion of the" operation of the electrical control for the control valve 40, a summary of operation will be helpful in understanding the objectives and advantages of the invention.

The control switch 40 has the valvespool y60 in the position shown in the drawing when the solenoid 72 is energized by closing of the contacts 80 and 82. This admits pressurized working fluid to the chamber 32, whereupon therpiston extension 36 is pushed tof the left moving the piston 10 to the left forcing compressed gas through the gas delivery conduit 1&6 and closing the check valve 20 to the intake conduit. When the piston eXtension 36 passes the bleeder holes 46, working fluid bleeds into the chamber 48 surrounded by the bellows 26 to act on the area 2 aiding in moving the piston 10 in its compression stroke. Y

At the end of the compression stroke the condenser 94 will have discharged its stored charge and the deenengization of the solenoid 70 will permit the valve spool I60 to be moved to the left by the spring 78. This will vent pressure from the working chamber 32 permitting the spring 30 to move the piston 10 back through its intake stroke forcing the working Huid out of the fluid chamber 32. Y

During movement of the piston in either direction the zone 24 outside of the expansible bellows26 is maintained ata neutral pressure by permitting the gas to ow through conduit 22 into or out of the supply conduit 23.

Thus, it will be seen that I have provided an improved compressor which attains the objectives and advantages hereinbefore set forth. The compressor utilizes an improved electrically controlled valve for supplying the working fluid and operates evenly and smoothly from a working uid at a higher pressure than the gas to becompressecl. The compressor is capable of being assembled into acompact unit and can be located in a small operating space and is reliable and capable of an extended operating life without the need of adjustment or repair.

I have, in the drawing and specification, presented a detailed disclosure of the preferred embodiment of my invention, but it is to be understood that I do not intend to limit the invention 4to the specific form disclosed,'but intend to cover all modilications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention.

I claim as my invention:

l. A gas compression pump and control operator assembly comprising in combination a gas compression chamber, a piston mounted in the chamber for reciprocation in an intake and discharge stroke, valve means communicating with Vthe chamber at a gas side of the piston for intake and delivery of compressed gas, a bellows connecting between a fluid side of the piston and the chamber, a chamber extension projecting into the chamber on the uid side of the piston, a piston extension slidably positioned in the chamber extension to form a fluid operating chamber, fluid bleed openings communicating between the fluid operating chamber and the interiorof the bellows, a control valve communicating with the fluid expansion chamber and adapted to direct a pressurized fluid into the fluid chamber for the compression stroke or to vent the chamber for the intake stroke of the piston, an electrical operating means for the valve, apressure responsive switch electrically connected to said accadr 6 electrical valve operating means and connectedto the iluid operating chamber, a fluid return delay valve connected between the pressure responsive switch and the fluid chamber and operative to retard the breakdown of the pressure in the switch with a reduction of pressure in the fluid chamber to thereby permit -the piston to move in its return stroke, spring biasing means moving the piston in its intake stroke, and an electrical condenser connected acrossthe electrical valveoperating means and continuing a supply of electricity to the valve operating means after the pressure responsive switch is opened with an increase of pressure in the vfluid chamber to thereby allow time for the piston'to move in its compression stroke after the pressure has increased within the uid operatingtchamber;

2, A iluid operated 'gas compressor comprising a compression chamber, a piston slidably mounted therein for gas compression by a-reciprocating movement, gas valve means communicating with the chamber at `the gas side of the piston for the intake of gas and the discharge of compressedv gas, fluid valve means communicating with the chamber at the uid side of the piston to alternately vent and direct a supply of pressurized fluid into the chamber to reciprocate the piston, spring means continually urging the piston tomove in its intake stroke, fluid valve operatingmeans connected to operate said iluidY valve means to alternate lthe position thereof and operate the piston, and a pressureresponsive means connected to the compression chamber at the iluid side of the piston and responsive to the pressure therein and connected to control the Avalve operating means to alternatethe position of the fluidvalve with predetermine pres-sure change and operate the piston. l

3. A uid operated gas compressor comprising a com .pression chamber, a-piston slidably mounted therein for gas compression by a reciprocating movement, gas valve means communicating with the chamber at the gas side of the piston for the intake and discharge of compressed gas, fluid valve means communicating with the chamber at the iuid side orthe piston to alternately vent and direct a supply of pressurized iiuid into the chamber to reciprocate the piston, spring means continually urging the piston to move in its intake stroke, electrical means for operating the' fluid valve means and periodically alternating its position to admit pressurized fluid to the compression chamber to move the piston in the compression stroke and subsequently relieving the pressure in the cham- .ber whereby said piston will be returned in its intake stroke, and a pressure responsive switch means connected to be responsive to the pressure on the uid side of the piston connected to the electrical means to operate the valve means and `drive the piston.

4.Y A piston operated compressor comprising a reciprocating piston operable by a pressurized Working iiuid and movable in a compression stroke and an intakeV stroke, a chamber in which the piston is slidably mounted, fluid valve means communicating with the chamber and movable between positions to alternately admit pressurized iluid to the chamber to move the piston in its compression stroke or to relieve the pressure and permit the pis- -ton to Imove in its intake stroke, spring means continually urging the pisto-n to move in its intake stroke, electrical means for operating the fluid valve means and periodically alternating its position, and a pressure responsive switch connected to said chamber and electrically connected to said electrical valve operating means to operate the valve and admit iluid to said chamber atlo'w pressure and release lluid from the chamber at high pressure Whereby the piston is caused to reciprocate.

5. A fluid operated gas compressor comprising a compression chamber, a piston slidably mounted therein for gas compression by a reciprocating movement, gas valve means communicating with the chamber at the gas side of the piston for the intake and discharge of compressed gas, lluid valve means communicating with the chamber at the fluid side of the piston to alternately vent and direct a. supply of pressurized lluid into 4the chamber to reciprocate the piston, means for moving the piston in a gas intake stroke when the lluid side is vented, and fluid valve operating means connected to the compression chamber at the lluid side of the piston and responsive to pressure therein, said valve operating means admitting pressurized lluid after a rst time delay period after the pressure has dropped in the chamber and venting the chamber after a second time delay period to relieve the pressure after the pressure has increased in the chamber, said first time delay period being a fixed period independent of piston position.

6. A piston operated compressor comprising a reciprocating piston operable by a pressurized working fluid and movable in a compression stroke and an intake stroke, a chamber in which the piston is slidably mounted, lluid valve means communicating with the chamber and movable between positions to alternately admit pressurized -lluid lto the chamber to move the piston in its compression stroke or to relieve the pressure and permit the piston to move in its intake stroke, means for moving the piston in an intake stroke when the tluid side is vented, electrical valve operating means connected to -the lluid valve means for changing its position, a pressure responsive switch connected to said chamber and electrically connected to said electrical valve operating means to operate the valve and admit lluid to said chamber at low pressure and release fluid from the chamber at high pressure whereby the piston is caused to reciprocate, and delay means operative to delay the operation of the fluid valve means after the switch operates at one of said pressures to permit the piston to move its full stroke.

7. A piston operated compressor comprising a reciprocating piston operable by a pressurized working fluid and movable in a compression stroke and an intake stroke, a chamber in which the piston is slidably mounted, fluid valve means communicating with the chamber and movable between positions to alternately admit pressurized sive switch connected to said chamber and electrically connected to said electrical valve operating means to operate the valve and admit lluid to said chamber at low pressure and release iluid from the chamber at high pressure whereby the piston is caused to reciprocate, delay means operative to delay the operation of the fluid valve means when the switch operates at a predetermined maximum pressure to permit the piston to move its full compression stroke, and a valve in the connection between the pressure responsive switch and the chamber to delay the drop of pressure in the switch when the pressure in the chamber drops to cause the switch to delay the operation of -the fluid valve means to permit the piston to move its -full intake stroke. I

8. A piston operated compressor comprising a reciprocating piston operable by a pressurized working lluid and movable in a compression stroke and an intake stroke, a working lluid chamber in which the piston is slidably mounted, lluid valve means communicating with the chamber and movable between positions to alternately admit pressurized lluid to the chamber to move the piston in its compression stroke or to relieve the pressure and 'is vented, electrical valve operating means connected t0 the lluid valve means for changing its position, a pressure responsive switch connected to said chamber and electrically connected to said electrical valve operating means to operate the valve and admit lluid to said chamber at low pressure and release lluid from the chamber at high pressure whereby the piston is caused to reciprocate, delay means operative to delay the operation of the iluid valve by the switch with a lirst pressure change in the tluid chamber to permit the piston to move a full stroke, and an electrical storage means connected to be charged when said switch is closed and discharging over a relatively short delay period .to continue energization of the electrical valve operating means after the switch is opened with a second pressure change in the chamber whereby the piston will complete its second stroke before operation of the valve.

9. A gas compressor assembly comprising a reciprocating piston operable by a pressurized working tluid and movable in a closed compression chamber in which 4the piston is slidably mounted, gas valve means communicating with the chamber at the gas side of the piston for the intake and discharge of compressed gas, a bellows of smaller cross-sectional area than the chamber connected between the piston and the end of the compression charnber opposite the gas valve means to form a iluid chamber isolated from the compression chamber wall, lluid valve means communicating with the interior of the bellows t0 alternately vent and direct a supply of pressurized uid into the bellows to reciprocate the piston, means for moving the piston in a gas intake stroke when the lluid side is vented, and lluid valve operating means connected to the `'lluid valve means and operative to periodically change the position of the valve to reciprocate the piston.

10. A gas compressor assembly comprising a reciprocating compressing piston operable by a pressurized working lluid and movable in a compression stroke and an intake stroke, a compression chamber in which the piston is slidably mounted, a working fluid chamber, an operating piston extension connected to the compressing piston slidably received by the fluid chamber, gas valve means communicating with the compression chamber at the gas side of the compressing piston, iluid valve means communicating with the working lluid chamber to alternately vent and direct a supply of pressurized iluid into the chamber to reciprocate the compressing piston and operating piston, means for moving the piston in a gas intake stroke when the fluid side is vented, lluid valve operating means connected to the lluid valve means and operative to periodically change the position of the valve to reciprocate the piston, an assist chamber exposed to the compressing piston, and means to supply working fluid to the assist chamber at a predetermined point in the `travel of the operating piston whereby the area of the compressing piston exposed to the assist chamber will aid in moving the piston for the remainder of the compression stroke.

l1. A gas compressor assembly comprising a reciprocating working piston operable by a pressurized working itluid and movable in a compression stroke and an intake stroke, a tubular member having an elongated inner first working lluid chamber in which the piston is slidably mounted, an elongated closed gas compressing chamber surrounding said tubular member and extending parallel thereto, a compressing piston slidably mounted in the compressing chamber, said compressing piston having a gas side and a lluid side with the working piston connected to the dluid side, a bellows of smaller cross-sectional area than the compressing chamber connected to the lluid side of the compressing piston and to the end of the compressing chamber and surrounding said tubular member to form a second working lluid chamber within the bellows, a conduit communicating between the compressing chamber on the gas side of the piston and the lluid side outside of said bellows and also communicating with a supply of gas, a reverse flow preventing valve in the conduit preventing escape of gas from the compressing chamber on the gas side of the piston, a gas delivery conduit leading from the compressing chamber on the gas side of the compressing piston, valve means closing ther delivery conduit for the intake stroke of the compressing piston, fluid valve means communicating with the interior of the bellows and with the interior of said tubular member to alternately Vent and direct a supply of pressurized Working fluid into the bellows and tubular member'to reciprocate the working piston and drive the compressing piston, means for moving the compressing piston in its gas intake stroke, and fluid va-lve operating means connected to the fluid valve means and operative to periodically change fthe position of the valve to reciprocate the pistons.

References Cited in the le of this patent UNITED STATES PATENTS 

